Like on all CRTs, in all new modes the monitor sees you need to manually adjust the positioning and size to perfection. Then things are remembered and stay so the next time that resolution is encountered again.

The FW900 has an auto-adjust function (accessible via a single button press) that's supposed to automatically setup a good 4:3 picture for you in the current video mode. However, at least on my FW900 it never worked completely correctly: after pressing the button and letting it do it's thing the picture was just a little tiny bit too narrow horizontally and the left/right edges weren't perfectly straight, instead the picture got slightly narrower upwards (trapezoid distortion). Really, the only purpose the button seemed to serve was to screw up good settings for any particular mode I had spend a lot of time to get just right if I accidentally hit it when the monitor controls weren't locked. 😜

In the end I just used a calculator and a ruler to draw small markings on the bezel of the monitor for 4:3 and 16:9, and then used those to adjust the monitor for video modes with these aspect ratios. Perhaps the automatic adjustment would have worked better when the monitor was new or on another unit altogether.

I'd get a GDM-F520 (4:3 but otherwise about just as good as the FW900) myself instead for use with old systems unless you also plan to use the same monitor with newer systems or you got the FW900 for free or very cheap. (well, at this point I'm not sure I'd get either anymore... IMO those late Sony CRTs indeed have a really really good picture when they work, but they don't seem to last as long as their mid-90s and earlier stuff did; my F520 or FW900 had some slight problems already even when I got them and now they don't work at all anymore... while the W900 is still working though the tube is really starting to show it's age and the even older PVM-2043 is also working)

it does not sound so good... 😀 did you see the actual prices of the fw900? on the ebay over 1000 eur with bidding.

🤣 at the prices. Fortunately TFTs aren't even really bad anymore except for the scaling at non-native resolutions.

Back when I bought it I got the FW900 for about 100 euros locally. I used it happily for many years with my PCs, and a PS3 and Xbox360 with an external DAC (HDFury), but in the end it started having issues first with the focus going sometimes out and then coming back in with a loud pop from inside (perhaps would have been fixable with cleaning or swapping the FBT), then later the screen started flashing green (in fact the green channel went so high during the flashes it made the retrace lines visible). At this point the tube's condition had also drifted towards worse, it took more and more time before everything looked right after power on. Eventually I had an accident where the monitor was dropped, IIRC it did still power on and "work" after that but the color flashes became even worse.

I still have the broken FW900, considering the current eBay prices I wonder if I could make some money by gutting the working parts from it and putting them up for sale... 😁 The postage costs for shipping anything from here to abroad with tracking are terrible though.

I also still have the broken F520. That one took very long to "warm up" even when I got it, and then in a few years it just stopped powering on completely (this is when I bought the FW900).